Surface treatment of particulate solids

ABSTRACT

THERE IS PROVIDED A FIRE FIGHTING FOAM COMPATIBLE FIRE FIGHTING POWDER COMPOSITION COMPOSED OF AN ALKALINE FIRE-EXTINGUISHING POOWDER FROM 1% TO 5% OF A PARTIALLY HYDROPHOBIC POWDERED SILICA HAVING A SURFACE AREA OF AT LEAST 10 SQUARE METERS PER GRAM AND CARRYING A SURFACE TREATMENT WITH A SILANE; THE SILANE HAS A HYDROPHOBIC GROUP WHICH IS NON-REACTIVE TO THE SILANOL GROUP ON THE SILICA SURFACE AND A FURTHER GROUP ON THE SILANE IS REACTIVE TO THE SILANOL GROUPS ON THE SILCA SURFACE. SUITABLY, THE HYDROPHOBIC GROUP CAN BE ALKYL AND THE REACTIVE GROUP CAN BE CHLORINE. THE DEGREE OF HYDROPHOBICITY MEASURED BY THE METHANOL TITRATION TEST IS IN THE RANGE OF 5 TO 35.

United States Patent Oflice Patented Aug. 20, 1974 3,830,738 SURFACETREATMENT OF PARTICULATE SOLIDS U. S. Cl. 252-4 4 Claims ABSTRACT OF THEDISCLOSURE There is provided a fire fighting foam compatible firefighting powder composition composed of an alkaline fire-extinguishingpowder and from 1% to 5% of a partially hydrophobic powdered silicahaving a surface area of at least square meters per gram and carrying asurface treatment with a silane; the silane has a hydrophobic groupwhich is non-reactive to the silanol groups on the silica surface and afurther group on the silane is reactive to the silanol groups on thesilica surface. Suitably, the hydrophobic group can be alkyl and thereactive group can be chlorine. The degree of hydrophobicity measured bythe methanol titration test is in the range of 5 to 35.

This invention relates to the surface treatment of particles and inparticular to the surface treatment of silica particles.

It is known that the surface properties of solids may be modified byapplying a silane or siloxane which often polymerises to form apolysiloxane or silicone layer on the surface. By such a treatment anormally hydrophilic surface is rendered hydrophobic. When thistreatment is applied to the individual particles of powders the flowproperties of the powders themselves, or of other solid powders to whichthe treated particles are added, are improved. However other propertiesmay be seriously impaired, for example properties which depend upon thepresence of hydrophilic groups on the surface or attraction to thesurface of other hydrophilic groups. As an illustration we observe thatmost known silane and siloxane treatments of silica render the surfaceso hydrophobic that the silica causes collapse of most aqueous foams.Thus we have found that for many purposes, of which foam compatibilityis one example, a particulate silica possessing properties intermediatebetween those of untreated and hydrophobic silica is necessary.

Thus according to the present invention there is provided asurface-treated powdered silica having a surface area of at least 10square metres per gram and possessing a degree of hydrophobicitymeasured by the methanol titration test hereinafter described in therange from 5 to 35.

According to another aspect of the invention there is provided apowdered silica having a surface area of at least 10 square metres pergram treated with an organosilicon compound to produce a degree ofhydrophobicity of the surface having a value from 5 to 35 as measured bythe methanol titration test hereinafter described.

The methanol titration test is an empirical test which distinguishes andidentifies powdered silicas possessing a degree of hydrophobicityintermediate between the untreated silica having a hydrophilic surfaceand the treated silica whose surface has been rendered completelyhydrophobic.

The said test is performed as follows:

The Methanol titration test" herein specified for the assessment of thedegree of hydrophobicity of a treated silicon is conducted as follows.0.2 gm. of the powder under test is added to 50 ml. of water in a 250ml. conical flask. Methanol is titrated from a burette until all thesilica is wetted which end-point is observed by the suspension of allthe powder in the liquid. Prior to the end-point being reached someparticles or agglomerates are observed to float on the surface of theliquid. The degree of hydrophobicity is quoted as the percentage ofmethanol in the liquid mixture of methanol and water when the end-pointis reached.

It is known that silanol groups are present on the surface of untreatedsilica and we believe that the replacement of silanol groups by groupsterminating in a hydrocarbon radical for example an alkyl or phenylradical changes the character of the surface from hydrophilic tohydrophobic. However it is not necessary to replace all the silanolgroups in order to effectively remove all hydrophilic character. It ispossible for the groups imparting hydrophibic character to so cover thesurface, and perhaps overlay the silanol groups, that the hydrophiliccharacter of the surface is lost and the silica is said to be completelyhydrophobic. We define the meaning of that term as being those finelydivided silicas giving a value of greater than 40 on the methanoltitration test hereinbefore described.

The silicas of intermediate hydrophobic character which we select asexhibiting a useful balance of properties give value of 5 to 35 on themethanol test. We prefer to use silica powders giving a value in thesame test of 15 to 35: these latter are observed to be preferable in avariety of applications hereinafter described. For the optimum balancebetween good flow properties and good compatibility with foams,especially firefighting foams, a silica giving values of 20 to 30 on thesame test is especially preferred.

Hydrophilic finely divided silica, sometimes referred to as high-area orcolloidal silica, may be produced by a variety of methods, for exampleby pyrogenic methods, or by the precipitation and drying of dispersedsilica sols. The surface area may be for example from 10 to 70 squaremetres per gram but is generally within the range to 400 square metresper gram, the particular surface area chosen (or conversely the size ofparticle chosen) depending upon the applications in mind. Any of thehydrophilic silicas described above are suitable as starting materialsfrom which the product of this invention may be made. However, we preferto use an Aerosil" type of silica of low bulk density.

The degree of hydrophobicity required in the product of this inventionmay be imparted to the silica by a variety of methods, for examplechemical treatment of the surface with a silane, a siloxane, or mixturesof silanes and siloxanes.

These methods of chemical treatment may be tailored to produce thedesired degree of hydrophobicity in at least three ways:

(1) Methyl groups are small and exert a high degree of hydrophobicitybut less hydrophobic hydrocarbon groups may be chemically-bound to thesurface, for example ethyl, phenyl and alkoxy methyl.

(2) The surface coverage of hydrophobic groups may be restricted either(a) by using a small concentration of reagent insufficient to react withall the silanol groups on the surface, or (b) by using a bulkyhydrophobic group so that steric factors prevent the packing ofsufficient groups. The first (a) is difficult to control reproduciblyand the second is a semi-theoretical concept which is believed tooperate when certain groups, e.g. trimethyl silyl or tertiary butylsilyl groups are added.

(3) The hydrophobic groups may be deliberately interspaced across thesilica surface with hydrophilic groups, for example alkoxy groups orpolyether groups, by

3 chemicallybonding such groups to the silica surfaceeThis may be doneeither by introducing both hydrophilic and hydrophobic groups into theone organosilicon compound or by reacting the silica with two compoundsdesigned to attach both groups separately.

One preferred method of so treating the surface comprises chemicalinteraction of powdered silica with a substantially anhydrous monomericsilane having the formula (R),,Si--(L) where n:l, 2 or 3, (R) is ahydrophobic group which is non-reactive to the silanol groups on thesurface and (L) is a group which is reactive to the silanol groups onthe silica surface.

The group L may include a lower all-toxy group, a chlorine or bromineatom or an acyl group. The lower alkoxy group is in general a groupcontaining up to five carbon atoms and may be either a primary or asecondary alkoxy group or an alkyl ether substituted oxy group, e.g. CHOCH CH O. It is sometimes advantageous to have two or three differentgroups represented by L because normally secondary alkoxy groups areless reactive to the silanol group on the surface than are primaryalkoxy groups and thus are more likely to remain intact and thus be ableto impart a degree of hydrophilic character to the surface after thesilane molecules with their hydrophobic group(s) R have become attached.The group L especially preferred is the ethoxy group and we haveobserved that a particularly suitable silane is a compound where R is agroup as hereinafter specified.

The group R may be a hydrocarbon group or a substituted hydrocarbongroup the substitution being with an atom or group which is stable andinert to the silica for example chlorine, fluorine, trifluoromethyl,alkyl or aryl ether. The hydrocarbon group will in general be an alkylor an alkenyl group containing from one to twenty carbon atoms, aphenyl, benzyl, tolyl, cyclopentyl or cyclohexyl group.

In the compounds when n is not equal to unity the group R may be thesame or different and one of these groups may include an alkyl etherlink or the whole group may be a polyalkylene ether group. It ispreferable when one group of (R) is a fairly large group, i.e. onecontaining more than four carbon atoms that the other groups comprising(R) be small groups, for example methyl or ethyl groups. Silanescontaining only one group R (i.e. where 11 1) are especially preferred,particularly when the other group is an alkoxy group, for example phenyltrichlorosilane, n-propyl trichlorosilane, methyl triethoxysilane, longchain alkyl triethoxy silane, of which the easiest to use is methyltriethoxysilane.

As an alternative to a compound as described above a silane having ahydrophilic substituent for either one R or one L group may be used. Thehydrophilic substituent is most conveniently a non-ionic polyetherchain, for example a polyethylene oxide chain.

Certain reactive silanes (for example dimethyldichlorosilane) are moredifficult to use than others because too readily they produce a silicawith a surface more hydrophobic than desired for this invention. Thecontrol of the reaction to provide just the desired balance betweenhydrophobic and hydrophilic character of the surface is more easilyachieved with for example trimethylchlorosilane and this is thereforepreferable to dimethyldichlorosilane in preparing the product of thisinvention. It is thought that the trimethylsilyl group being a bulkygroup will probably not allow too great a coverage of the surface withhydrophobic groups. Thus the nature and size of the groups present inthe silane, together of course with the surface area of the silica,should be taken into account when deciding the concentration of silaneto react with the silica.

In order to ensure that at least a substantial proportion of the silanedoes not polymerise before it reacts with the surface the silane ispreferably kept substantially dry until it contacts the surface ofthe-silica. After the surface has been treated with the silane, chemicalreaction between the silane and the surface may be promoted by waterand/or by heat.

Traces of water are almost always present at a siliceous surface andthere may be sufficient water present in the silica to promote thegeaction with the silane. Thus a silica of high surface area may containup to 3% by weight of water (but it is desirably from (LS-1.5%) as thisconcentration of water will conveniently promote the reaction of themonomeric silane withthe silica particles. It may be necessary to reducethe moisture content of the silica, for example by drying for a periodof about one hour at a temperature of 50 C. C. The silane may then beadded to the silica, intimately mixed and if the chemical reaction isslow it is convenient to heat the treated silica, optionally in a slownitrogen stream, to a temperature of 4D C.l00 C., preferably 55 C.70 C.The heating is preferably conducted under an atmosphere containingwater, for example in a closed vessel, or in an oven through whichcontrolled amounts of steam are passed. There is less need to heat thesilica when reactive compounds such as (CH SiCl or [(CH Si] O are used.

The concentrations of silane or siloxane preferred for the treatment ofhigh-area silica are at least 1%, for example from 1% to 30% by weightof silane added to the silica, but it is preferably 10% to 20% when analkoxysilane is used and 5% to 15% when a chlorosilane is used. Theincrease in weight may be limited by the extent of coverage of thesurface possible, steric factors probably being more important than thetotal concentration of silane present.

A treatment of a siliceous surface as described above imparts a degreeof hydrophobic character to the surface but we believe it does notrender it completely hydrophobic.

Silicon compounds other than silanes may be used to react with thesilanol groups on the silica surface and produce the product of thisinvention. Symmetrical siloxanes and silazanes and particularly suitableperhaps because they have a tendency to split into two or more identicalreactive groups (SiR containing one silicon atom and thus groups areattached to the silica in a similar way to the reaction with monomericsilanes of formula R SiL. For example the compoundshexamethyldisiloxane, hexamethyldisilazane,sym-divinyl-tetramethyldisiloxane may be conveniently used to producesilica of intermediate hydrophobicity.

Siloxane polymers are difficult to use to react with a silica to producethe desired degree of hydrophobicity for this invention. They reactreadily with silica but there is a strong tendency for the silica tobecome more hydrophobic than is desired in the present invention.However a polysiloxane containing hydrophilic groups as substituents onthe silicon atoms may conveniently be used: the hydrophilic groups,which include for example oxyalkylene groups or hydroxy alkylene groups,will balance the hydrophobic character of the polysiloxane chain and asilica in accordane with this invention may be produced. Thus a suitablepolysiloxane may have a general formula as follows:

(O CH CHP O CH and by appropriate choice of the sizes of n, m and z acoating may be produced on a powdered silica of the desiredhydrophobicity for the product of this invention.

Polysiloxanes are sometimes produced from a reaction between alkyl oraryl chlorosilanes in the presence of water. The silanes used aregenerally mixtures of mono, di and trichlorosilanes of general formulawhere R is an alkyl or aryl group and x is l, 2 or 3.

A variety of lengths of chain or degrees of branching may be produced byaltering the relative proportions of the silanes may be for example:

Percent Mono-(R SiCl) 2 to 5 Di(R SiCl 55 to 82 Tri( RSiCl to 30 Theymay be added as a vapour mixture to powdered silica and reaction willoccur on the surface of the particles because generally sufiicient wateris present but further water may be added if necessary. A mixture ofsilanes as above wherein R is CH is preferred.

In many other branches of technology where silica is used a partiallyhydrophobic silica is useful particularly in applications where aqueousand non-aqueous systems are involved. The peculiar character of itssurface imparts to products properties hitherto not possessed by priorart samples of silica, but it should be stressed that the surfacetreatment requires to be performed carefully and with precision in orderto obtain the product having the degree of hydrophobicity hereinspecified.

Hydrophobic silica is widely used as a flow additive for powders, anadditive which prevents caking on storage and facilitates removal fromthe storage vessel and also facilitates the flow of the powdersubsequently. The partially hydrophobic silica herein described isuseful for this application in the concentration range 0.1% to 5%,preferably 0.5% to 2.5% because it minimises the tendency of thehydrophobic form to cause breakdown of a foam. Thus our silica may beadvantageously used as a flow additive to fire-fighting powders torender them foam compatible, a property which it is very desirable thata fire-fighting powder possesses in order that the rapid flameextinguishing effect of the dry powder may be followed up with theapplication of a blanket of foam. Thus, a fire may be fought by applyingto the fire a combination of an aqueous fire-fighting foam and apowdered composition comprising the above-identified alkalinefire-extinguishing powder and partially hydrophobic powdered silica.

Powders and particulate solids in general may be usefully treated withpartially hydrophobic silica as a freeflow or anti-caking additive, andit is especially useful when added to a powdered solid required in useto come into contact with or function in an aqueous system. Thus thissilica may be advantageously added to solid fertilisers and to detergentor pharmaceutical powders to provide a desirable balance between stablestorage with the minimum absorption and the ability to be suspended ordissolved in water for use. This tom of silica is particularlyadvantageous in detergent powders which are required to produce a stablefoam, for example a foamed gel as described in our copending U.S.Application No. 121,186.

Silica is used in thickening silicone oils to make greases and becausethe hydrophilic/hydrophobic character of the surface is important thetreated silica of this invention provides an improvement over prior artsilicas. It has been observed that the work stability (measured by awetted cone peuetrometer) of a silicone oil/ grease is improved if from5% to 30% of a partially hydrophobic silica as herein described is addedto the composition. The preferred concentration is from 12% to 20% byweight.

The partially hydrophobic silica also provides improved emulsions withother oils and creams, for example cosmetic creams such as hand creamsand face creams. Gel paints and thixotropic and emulsion paints may beimproved by the incorporation of partially hydrophobic silica, a betterblend of the solid being obtained with both hydrophobic or hydrophilicingredients.

In many organic foam formulations a filler or thickener is desirable butit is clearly necessary for the additive to be one which will not causeany instability of the foam. Consequently foam formulations for makingeither synthetic rubber (for example polyurethane rubber) or naturalrubber foams are improved by the use of a partially hydrophobic silica.

In silicone rubber technology silica is used as a filler but a silane orsiloxane modified silica is preferable in that it may be more easilyincorporated chemically into the rubber structure and therefore give animproved product. As an anti-blocking aid in plastic films, for examplea packaging film, and as an additive for the improvement of theelectrical resistivity of plasticised polymers, for example polyvinylchloride, the silica of this invention will find application.

The invention is illustrated but in no way limited by the followingExamples:

EXAMPLE 1 20 parts of triethoxymethylsilane were sprayed on to parts ofAerosiP silica of surface area 200 square metres per gram and containing2% of water. The silane and silica were mixed thoroughly in a sealedcone-mixer at room temperature for two hours. Mixing was continued at atemperature of 60 C. for a further 24 hours following which the mixerwas opened up to the atmosphere. The mixture was dried for six hours inthe same apparatus by continuing the mixing operation for six hours withthe vent open to allow the ethanol formed to escape.

EXAMPLE 2 30 parts of triethoxymethylsilane were sprayed over 100 partsof silica of surface area 200 square metres per gram and "thoroughlymixed at room temperature. The mixture was spread in open trays whichwere placed in an oven maintained at 60 C. into which steam was passedto maintain a constant humidity. The reaction was allowed to continuefor 12 hours. The supply of steam was then cut off and the mixture driedin the same oven for a further period of six hours.

EXAMPLE 3 A laboratory test for the foam compatibility was used toevaluate the treatments given to the silica.

1 g. of treated silica or 20 g. of a fire-fighting dry powder containing1.5% silica are mixed with 30 mls. of petrol in a small beaker. Theslurry is poured into a 2 litre measuring cylinder, 5 mls. of additionalpetrol are used to wash out the beaker. 25 mls. of petrol are pouredinto another 2 litre measuring cylinder as a blank. Both measuringcylinders are weighed. The two cylinders are both filled with proteinfoam from a foam extinguisher. (The foam should have an expansion ratioof between 7 and 8.) A stopwatch is started as the cylinders are filled.The two cylinders are reweighed and the half drainage time of both thesample and the blank measured. The values of may thus be calculated(percent RC.)

IOOX

The test was also applied to g. of dry fire-fighting powder containing 1g. of the silica as an additive. The results obtained by the foamcompatibility test for differently-treated silicas and for 1.5% of thesame treated silicas added to a fire-fighting powder made by the processdescribed in Example 1 of our UK. Pat No. 1,168,092 are presented inTable 1.

Samples of dry chemical powder which give results of greater than 50 forthe percent RC. values are normally satisfactory in the US. Underwriterstest for fire-fighting chemicals.

Silica treated with methyltriethoxysilane (as in Table 1) was added to asodium bicarbonate fire extinguishing powder and percent EC. values ofgreater than 50 were obtained typically in the range 60 to 80.

EXAMPLE 4 An Aerosil silica (Aerosil" 200) was treated, with a siliconcompound as shown in Table 2 for a period of time ranging from 48-72hours at room temperature followed by a heat treatment at a temperaturewithin a the range 50 C.-70 C. to complete the reaction. The resultingsilica was given a methanol titration test for hydrophobicity and it wasobserved that according to the proportion of silicon compound used andthe length of time reacted, the figures obtained for the degree ofhydrophobicity fell into certain ranges as shown in Table 2.

TABLE 2 Titration Test Degree of hydrophobicity Silicon compound:(measured by the Methanol) Methyl vinyldichlorosilane 34-44 Penhyltrichlorosilane 15-25 Trimethyl chlorosilane -42 Dimethyldiethoxysilane25-42 n-Propyl trichlorosilane 25-35 Hexamethyldisiloxane 20-30Diphenyldichlorosilane 15-35 Methyl triethoxysilane 15-40 C -alkyltriethoxysilane 10-35 EXAMPLE 5 15 parts of triethoxymethylsilane weresprayed on to 100 parts of Aerosil" silica contained in a heated ribbonmixer. The temperature of the silica during the spraying was C. C. TheAerosil had a specific surface of 200 square metres per gram andcontained 1% moisture. Mixing was continued at 50 C.-55 C. for a periodof 2 hours. The temperature was then increased to C.- C. for 12 hours.During this period a slow stream of nitrogen was blown across thesurface to remove byproduct ethanol, and the flow of nitrogen wasincreased during a final two-hour drying period.

EXAMPLE 6 25 parts of triethoxymethylsilane were sprayed over 100 partsof silica (Aerosil surface area 200 square metres per gram). The silicaand silane were thoroughly mixed in a triple cone mixer for 24 hours atambient temperature,

The treated silica was spread on to open trays 1 /2" in depth. Thesewere placed in an oven maintained at 65 C. into which steam was passedso that the atmosphere was kept humid. The reaction was allowed tocontinue for 12 hours. The steam was then cut off and the silica driedin the same oven for a further 2 hours.

Analysis of the concentration of ethoxy groups on the silica gave valuesbetween 1.1 and 1.4 for the ratioof ethoxy:total carbon, the averagevalue being "1.25; The value of 1.25 indicates that the mean molar ratioof ethoxy to methyl groups on the silica was 1:1. i

What we claim is:

1. A fire-fighting foam compatible fire-fighting powder compositionconsisting essentially of an alkaline fire extinguishing powder and from1% to 5% of a partially hydrophobic powdered silica having a surfacearea of at least 10 square metres per gram and carrying a surfacetreatment with a silane of the formula (R),,,Si-(L) where n has thevalue of 1, 2 or3 and R is a hydrophobic group which is non-reactive tothe silanol groups on the silica surface and is a hydrocarbon group or asubstituted hydrocarbon group, the hydrocarbon group being selected fromalkyl and alkenyl of up to 20 carbon atoms, phenyl, benzyl, tolyl,cyclopentyl, cyclohexyl, and a polyoxyethylene, the substituent beingselected from chlorine, fluorine, trifluoromethyl, or alkyl ether and Lis a group which is reactive to the silanol groups on the silica surfaceand is a chlorine or an alkoxy group containing up to five carbon atoms,and possessing a degree of hydrophobicity measured by the methanoltitration test in the range 5 to 35.

2. A method of imparting to an alkaline fire extinguishing powdercompatability with aqueous foams consisting essentially of intimatelymixing the powder with 0.1% to 5% of a partially hydrophobic powderedsilica having a surface area of at least 10 square metresper gram andcarrying a surface treatment with a silane of the formula R) Si(L) wheren has the value of 1, 2 or 3 and R is a hydrophobic group which isnonreactive to the silanol groups on the silica surface and is ahydrocarbon group or a substituted hydrocarbon group, the hydrocarbongroup being selected from alkyl and alkenyl of up to 20 carbon atoms,phenyl, benzyl, tolyl, cyclopentyl, cyclohexyl, and a polyoxyethylene,the substituent being selected from chlorine, fluorine, trifluoromethyl,or alkyl ether and L is a group which is reactive to the silanol groupson the silica surface and is a chlorine or an alkoxy group containing upto five carbon atoms, and possessing a degree of hydrophobicity measuredby the methanol titration test in the range 5 to 35.

3. A method as claimed in claim 2 wherein the concentration of partiallyhydrophobic silica is from 0.5% to 2.5%.

4. A method of fighting a fire comprising applying to the fire thecombination of an aqueous fire-fighting foam and the powder compositionas claimed in claim 1.

References Cited UNITED STATES PATENTS 3,621,917 11/1971 Rosen et al.252-3 X 2,993,809 7/1961 Bueche et al 117100 3,677,347 7/1972 Rosen 2523X 3,531,407 9/1970 Phillips et al 252-2 OTHER REFERENCES Kirk-Othner,Encyclopedia of Chemical Techonlogy 2nd ed., Vol. 18, p. 67, 1969.

MAYER WEINBLATT, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION Patent No. 3,830,7384 Dated i ust 20, 1974 I ht ARNOLD GEORGE COTTRELL It is certified thaterror appears in the abov eidentified patent and that said LettersvPatent are hereby corrected as shownbelow:

IN THE ABSTRACT 0F THE- DISCLOSURE:

Column 1, line 17, change "l%" to '--O.l%-.

IN THE CLAIMS! Claim 1, (column 8, line '15) change "1%" to (column 8,line 24) change "cyclopentyl," to -cyclopentyl and-;

, (column 8, lines 24 and 25) delete "a polyoxyethylene,".

Claim 2, (column 8, line 44) change "cyclopentyl,

to --cyclopentyl and;

(column 8, line 44) delete "a polyoxyethy1ene,".

Signed and sealed this 1st day of July 1975.

SEAL) Attest C. MARSHALL DANN RUTH C. I-IASON Commissioner of PatentsAttesting Officer and Trademarks UNITED STATES PATENT OFFICE CERTIFICATECORRECTION Patent No. 3,830,738 Date Ammstgo, 1974 I I ARNOLD GEORGECOTTRELL It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown'below:

IN THE ABSTRACT OF THE DISCLOSURE:

IN THE CLAIMS! Column 1', line 17, change "1%" to "-0.l%-.

Claim 1, (column 8, line '15 change "1%" to -0.l%---; I I

(column 8, line 24) change "cyclopentyl," to --cyclopentyl and-;

(column 8, lines 24 and 25) delete "a polyoxyethylene,".

Claim 2, (column 8, line 44) change "cyclopentyl,

to -cyclopentyl and-;

(column 8, line 44) delete "a polyoxyethylene,".

Signed and sealed this 1st day of July 1975.

(SEAL) Attest C. MARSHALL DANN RUTH C. MASON Commissioner of. PatentsAttesting Officer and Trademarks Patent No. 3,830,738 Dated Auqust go,1974 Inven tor s) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

IN THE ABSTRACT OF THE DISCLOSURE:

Column 1, line 17, change "1%" to -0.l%--.

IN THE CLAIMS! Claim 1, (column 8, line 15) change "1%" to (column 8,line 24), change "cyclopentyl," to -cyclopentyl and-;

(column 8, lines 24 and 25) delete "a polyoxyethylene,".

Claim 2, (column 8, line 44) change "cyclopentyl,

to --cyclopentyl and--;

(column 8, line 44) delete "a polyoxyethylene,".

Signed and sealed this 1st day of July 1975.

(SEAL) Attest:

I-IARSHALL DANN- RUTH C. I'IASON Commissioner of Patents ArrestingOfficer and Trademarks

